Highly Active Supported Pt Nanocatalysts Synthesized by Alcohol Reduction towards Hydrogenation of Cinnamaldehyde: Synergy of Metal Valence and Hydroxyl Groups.

The hydrogenation of α,β-unsaturated aldehydes to allylic alcohols or saturated aldehydes provides a typical example to study the catalytic effect on structure-sensitive reactions. In this work, supported platinum nanocatalysts over hydrotalcite were synthesized by an alcohol reduction method. The Pt catalyst prepared by the reduction with a polyol (ethylene glycol) outperforms those prepared with ethanol and methanol in the hydrogenation of cinnamaldehyde. The selectivity towards the C=O bond is the highest over the former, although its mean size of Pt particles is the smallest. The hydroxyl groups on hydrotalcite could act as an internally accessible promoter to enhance the selectivity towards the C=O bond. The optimal Pt catalyst showed a high activity with an initial turnover frequency (TOF) of 2.314 s(-1). This work unveils the synergic effect of metal valence and in situ promoter on the chemoselective hydrogenation, which could open up a new direction in designing hydrogenation catalysts.